davidson



July 12, 1955 T. o. DAVIDSON DRAGLINE COUNTERWEIGHT 2 Sheets-Sheet 1 Filed April 11, 1951 REVOR O DAWDSON INVENTOR. BY W 7W ATI' ORNEY.

y 12, 1955 T. o. DAVIDSON 2,712,701

DRAGLINE COUNTERWEIGHT Filed April 11, 1951 2 Sheets-Sheet 2 TREVOR o. DAWDSON,

JNVENTOR.

AZTOR/VE Y Patented July 12, v 1955 fiice 2,712,701 DRAGLINE C OUNTERWE IG HT Trevor 0. Davidson, Milwaukee, Wis.,

Bucyrus-Erie Company, South Milwaukee, poration of Delaware Application April 11, 1951, Serial No. 220,370 6 Claims. (Cl. 37 -135) assignor to Wis., a cor- Counterweights of this type not only counterbalance the weight of the boom, dipper handle and dipper, but are also so connected to the hoisting machinery that they provide a large portion of the force necessary to carry out the digging and load-raising motions, thus permitting a substantial decrease stantial advantages well known in the art.

In shovel excavators, one motion digs and hoists. Consequently, a single live counterweight, associated with the means providing this motion, can be used to counterbalance and also to assist in both the'digging and hoistingoperations. In dragline excavators, however, there are separate and independent digging and hoisting motions, which has been thought to necessitate two live counterweights. The complications foreseen from the use of two live counterweights has resulted in foregoing the use of live counterweights on dragline, with a consequent loss of advantages.

The principal object of this invention is to provide a counterbalancing apparatus for use with draglines, involving a single live counterweight, which will bring to draglines the advantages previously available only to shovel excavators.

Another object of the invention is to provide a live counterweight apparatus for draglmes which, elimination and simplification of machine, will not substantially increase the cost of the machine.

In addition to the principal objects, above stated, a number of novel and useful details have been worked out, which will be readily evident as the description progresses.

The invention consists in the novel parts, and in the combinations and arrangements thereof, which are defined in the appended claims, and of which three embodiments are exemplified in the accompanying drawings, which are hereinafter particularly described and explained.

Throughout the description the same reference number is applied to the same member or to similar members.

Figure l is a side elevation of a dragline excavator embodying the invention.

Figure 2 is a rear view showing the details of the counterweight and its supporting rope.

Figure 3 is a top view showing in detail the hoisting machinery of one embodiment of the invention.

Figure 4 is a top view showing in detail the hoisting machinery of a second embodiment of the invention.

Figure 5 is a top view showing in detail the hoisting machinery of a third embodiment of the invention.

in the size of the motors and other subother elements of the 1- Referring first to Figure 1, it is seen that 11 is the main revolving frame of a dragline excavator, carried by ground support 12. Pivoted at the front end of frame 11 is a boom 13, suspended from tower form of an A-frame, on frame 11, by means of tackle 15.

Dragline bucket 17 is suspended from the outer end of boom 13 by one end of a hoist rope 18, which passes over sheave 19 and is fastened at its other end to hoist drum 20. Drum 29 is rotated by conventional reversible motor means M, for raising and lowering bucket 17.

Also connected at one end to bucket 17 is a drag rope 21, which is connected at its other end to drag drum 22. Drum 22 is rotated, by conventional motor means M, to wind in and pay out rope 21.

Referring also to Figure 2 it is seen that tower 14 supports a live counterweight 23, which is carried by rope tackle 24, of an even number of parts and engaging sheaves 25 on the counterweight and sheaves 26 adjacent the top or" the tower.

Now referring also to Figure 3, it is seen that one end of rope 24 is connected to a drum 27, which is directly geared to hoist drum 29 in such a way that as drum 24 winds in rope 18 drum 27 will pay out rope 24, and as drum 29 pays out rope 13 drum 27 will wind in rope 24.

The other end of rope 24 is connected to a drum 28, which is directly geared to drag drum 22 in such a way that as drum 22 Winds in rope 21 drum 28 will pay out rope 24, and as drum 22 pays out rope 21 drum 28 will wind in rope 24.

For the two drums 20 and 27 there may be substituted a single two-part drum means 29, in which event the two ropes 18 and 24 are oppositely wound onto the drum means. A similar substitution 39 may be Figure 5. In this embodiment,

part 2911 of drum the hoist and drag movements and the movement of the The two ends of counterweight rope 24 The inner flanges of hoist drum 20a and drag drum 22!; have gears 40 and 41 respectively mounted about their peripheries, which serve as the sun gears of the spur diiferential gear means. Gear 4% is in mesh with pinion 36, and gear 41 with pinion 38. Hoist and drag ropes 18 and 21 are respectively wound onto their drums 2th; and 22a in a direction opposite to the winding of counterweight rope 24 about its drum 31.

From the foregoing description it will be seen that the operation of the third embodiment of the invention is as follows. During hoisting of the bucket 17, with drag drum 22a held by a brake (not shown), rotation of drum 20a will force rotation of pinion 36. Due to the interconnection of pinion 36 with stationary drum 22a, this rotation of pinion 36 can occur only through rotation of drum 31 in the same direction as drum 2%. Since ropes 1S and 24 are oppositely wound, the winding in of rope 18 to hoist the bucket results in paying out of rope 2i, which lowers counterweight 23 as previously explained.

14, preferably in the a It is now obvious that lowering the bucket 17 will result in raising the counterweigh Similarly, if drag drum 22a is rotated to drag in bucket 17, hoist drum 20a being held from rotation, the counterweight will be lowered; and if the drag drum is rotated to pay out drag rope 21, the counterweight will be raised. Simultaneous rotation of drums 26a and 22a to wind in or pay out their ropes 18 and 21 will merely cause a faster lowering or raising of counterweight 23.

It is obvious that instead of aflixing both ends of rope 24 to counterweight drum 31, one end of the rope could be fixed to the drum and the other end to the counterweight. It is equally obvious that although the spur differential gear system is shown and described, any of a number of epicyclic trains could be used without departing from the spirit of the invention.

For best operation of the invention, and best propor tioning of the excavator, a tackle 24 in four parts is preferred with a counterweight 23 of approximately four times the weightrof the empty bucket 17. counterweight tower 14 must then have a height slightly greaterthan one-fourth the sum of the maximum movements of the hoist rope 18 and the drag rope 21, plus the vertical dimension of counterweight 23. Normally, maximum travel of the counterweight occurs as the bucket moves 1.-

from digging position (position A, Figure l) to dumping position (position C). Movement from digging position to hoist position (position B) requires lesser counterweight travel.

The live counterweight obviously serves the same counterbalancing purpose on a dragline as the conventional dead counterweight. Furthermore, since the live counterweight is indirectly connected to both the hoist and drag ropes, its great weight is utilized to assist the hoisting and dragging (digging) operations. This permits use of a smaller power plant, or the use of a larger bucket with the same power plant. With a given size power plant the live counterweight permits the use of a bucket approximately one-third larger than can be used with a dead counterweight. A further advantage is that, when using an electric power plant, the hoisting and digging accelerations will be higher.

If, rather than increasing bucket size for the same powerplant, a smaller power plant is used for the same bucket size, the live counterweight provides the following advantages in an electrically-powered machine: (1) smaller power plant, with consequent lower cost; (2) less electrical energy consumption; (3) lower peaks of electrical intake and regenerative output of the power means; (4) better acceleration due to decreased inertia in the smaller electric motors, resulting in faster, more responsive operation; (5) smaller brake drums and bands, since bucket weight is mostly carried by the counterweight, which also betters acceler tion due to less inertia and lowers cost. V

The counterweight plus friction forces of the tackle may be less or greater than the weight of the bucket. If less, the bucket may be returned from raised (dumping) to digging position by the force of gravity, with assistance, if desired, by applying the power source to raise the counterweight. If greater, it will be necessary to apply power to'raise the counterweight when it is desired to lower the bucket.

The tackle may be of any number of parts, though four parts appears preferable, the necessary height of the counterweighttower decreasing and the required counterweight mass increasing vwith increase in the number or" parts.

It is obvious that for the rope shown and described any equivalent flexible tension means, such as chains, could be substituted, without departing from the invention. It

is equally obvious that any or all of the drums about which the counterweight rope is wound could have tapered profiles for the purpose of increasing or decreasing the force assisting the dragging and hoisting motions at those points where greater or lesser. assistance is desirable.

Having now described and illustrated three forms of the invention, it is to be understood that the invention is not to be limited to the specific form or arrangement of parts hereinbefore described and shown.

I claim:

1. In a dragline excavator having a main frame, and a digging bucket supported by a hoist rope and moved for digging by a drag rope, the combination therewith of: a counterweight tower supported by the main frame; a vertically movable counterweight suspended from the tower by a counterweight rope; first rotatable winch means about which the hoist rope is wound in one direction and about which one end of the counterweight rope is wound in the other direction; second rotatable winch means about which the drag rope is wound in one direction and about which the other end of the counterweight rope is wound in the other direcetion; and reversible motor means to at will cause rotation of either or both of said winch means. 7

2. In a dragline excavator having a main frame, a digging bucket supported by a hoist rope, a hoist drum to wind in or pay out the hoist rope to raise or lowerthe bucket, a drag drum to at will pay out or wind in adrag rope connected to the bucket, and reversible motor means to at will cause rotation of either or both of said drums,

the combination with these conventional features of: first drum means associated with the hoist drum to rotate when the hoist drum rotates; second drum means associated with the drag drum to rotate when the drag drum rotates; a counterweight tower supported by the main frame, a vertically movable counterweight suspended from said tower by a tackle which includes a counterweight rope, one'end of said counterweight rope being connected to the first drum means to pay out the counterweight rope when the hoist drum rotates to raise the bucket and to wind in the counterweight rope whenv the hoist drum'rotates to lower the bucket, and the other end of said counterweight rope being connected to the second drum means to pay out the counterweight rope when the drag drum rotates to wind in the drag rope. and to wind in the counterweight rope when the drag drum rotates to pay out the drag rope.

3. In a dragline excavator having a digging bucket, a first power-driven winch drum means operatively connected to the bucket to hoist and lower the bucket, and a second power-driven winch drum means operatively connected to the bucket to haul the'bucket in for digging and release it for dumping, the combination of: a vertically-movable counterweight mass; and means for raising and lowering'the counterweight mass, said means being operatively connected to the first drum means to lower the mass when the bucket is hoisted and to raise a the mass when the bucket is lowered, and being operatively connected to the second drum means to lower the mass when the bucket is hauled in and to raise the mass when the bucket is released, whereby either lowering the bucket or'releasing the bucket from being dragged stores up potential energy in the mass to assist in hoistingthe bucket and hauling in 'the bucket. V e

4. In a dragline excavator having a main frame and a digging bucket controlled by hoist and drag means, the combination therewith of a counterweight tower supported by the main frame, and a counterweight suspended from the tower by a tackle, the tackle including arope one end of which is operatively connected to the'hoist means to assist the hoisting motion and the other end of which is operatively connected to the drag means to assist the dragging motion,

I 5. In a dragline excavator having a main frame and a digging bucket supported by a hoist rope and actuated for digging and dumping by a drag rope, a driving mechanism for operation of said bucket including: a first drum for winding in and paying out the hoist rope; a second out rope will rotate the third drum to Wind-in rope.

6. In a dragline excavator having a main frame and a digging bucket supported by a hoist rope and actuated for digging and dumping by a drag rope, a driving mechanism for operation of said bucket including: a first drum for winding-in and paying-out the hoist rope; a second drum for winding-in and paying-out the drag rope; a vertically-movable counterweight; a third drum operatively connected to the counterweight to move the counterweight when rotated; and an epicyclic train operatively interconnecting the three drums, said epicyclic train comprising a differential gear system including: a first sun gear carried by the first drum; a second sun gear carried by the second drum; and a plurality of planet gears rotatably carried by the third drum, at least one of the planet gears being in mesh With the first sun gear and at least one of the planet gears being in mesh With the second sun gear, and at least one of the planet gears being in mesh with another of said gears.

References Cited in the file of this patent UNITED STATES PATENTS 1,100,052 Burke et al. June 16, 1914 1,318,467 Travell Oct. 14, 1919 1,973,136 Atkinson Sept. 1, 1934 2,267,614 Martinson Dec. 23, 1941 FOREIGN PATENTS 363,006 Germany Nov. 9, 1922 

